Hybrid thixotropic rocket and jet fuels comprising oil in water emulsions



Nov. 14, 1967 K J. LISSANT 3,352,109

HYBRID THIXOTROPIC iiOCKET AND JET FUELS COMPRISING OIL IN WATEREMULSIONS Filed May 4, 1966 6 Sheets-Sheet 1 FIG. I

RELATIVE EFFECTI VENESS 0 1 m "an" I] n I I r Nov. 14, 1967 K. J.LISSANT HYBRID THIXOTROPIC ROCKET AND JET FUELS COMPRISING Filed May 4,1966 OIL IN WATER EMULSIONS FIG. 2

6 Sheets-Sheet 2 Q G O (2) WEIGHT PARTS ETO/n-DECANOL 2.0 (I) WEIGHTPARTS PRO/n-DECANOL.

Nov. 14, 1967 K. J. LISSANT OIL IN WATER EMULSIONS Filed May 4, 1966FIG. 3

6 Sheets-Sheet 5 2) MOLES ETO PER PHENOLIC UNIT OF RESIN Q (I)MOL.ES PROPER PHENOLIC UNIT OF RESIN Nov. 14, 1967 K. J. LISSANT 3,352,109

HYBRID THIXOTROPIG ROCKET AND JET FUELS COMPRISING Filed May 4, 1966RELATIVE RELATIVE RELATIVE EFFECTIVENESS EFFECTIVENESS EFFECTIVENESS (a)WEIGHT ETO OIL IN WATER EMULSIONS 6 Sheets-Sheet 4 FIG. 4

(I) WEIGHT BUO n o I I I I I l o 5 IO I5 WEIGHT PART OF FINAL ETOADDITION FIG. 5

OI 1II II n I O 5 IO I5 2 0 25 WEIGHT PART OF FINAI ETO ADDITION FIG. 6

I I I I I 0 5 IO I5 20 WEIGHT PART OF FINAL ETO ADDITIO FIG. 7

K. J. LISSANT Nov. 14, 1967 HYBRID THIXOTROPIC ROCKET AND JET FUELSCOMPRISING OIL IN WATER EMULSIONS 6 Sheets-Sheet 5 Filed May 4, 1966SCHEMATIC OF FIVE-DIMENSIONAL COM POSITION SPACE HYBRID THIXOTROPICROCKET AND JET FUELS COMPRISING OIL IN WATER EMULSIONS Filed May 4, 19666 Sheets-Sheet 6 FIG. 9

RELATIVE POSITION AFTER STEP FOUR NOliIClCIV O13 "IVNIJ United StatesPatent 12 Claims. (Cl. 60-217) This application is a continuation of myapplication Ser. No. 302,177 now abandoned, entitled Hybrid Fuels I,filed on Aug. 14, 1963, and is copending with each of the followingapplications.

Ser. No. 286,877, now abandoned, filed May 20, 1963, titled StableEmulsions; Ser. No. 302,001, filed Aug. 14, 1963, titled Hybrid Fuel II;Ser. No. 411,103, filed Nov. 13, 1964, titled Emulsion Preparation; Ser.No. 541,738, filed Apr. 11, 1966, titled Treating Thixotropic Emulsions.

This invention relates to high internal phase emulsions; to rocket andjet fuels; and to the use thereof in rocket and jet propulsion. Moreparticularly this invention relates to such fuels having thecharacteristics of both liquid and solid fuels (i.e. they are hybridsolidliquid fuels). Still more particularly this invention relates tohybrid solid-liquid fuels which are especially prepared high internalphase emulsions of one combustible material and a second combustibleand/or volatile material which is immiscible in said first combustiblematerial, said emulsion being prepared by means of an emulsifying agentwhich is capable of forming an emulsion having the characteristics of asolid fuel when at rest and a liquid fuel when force is exerted on it,such as by the shear of pumping, mixing, etc. This invention alsorelates to said hybrid fuels containing certain finely divided solidssuspended therein, such as for example, metals, salts, etc.

In the field of rocket and jet fuel propulsion two general types offuels are usedsolid fuels and liquid fuels. Both types have intrinsicadvantages and disadvantages. For example it is highly advantageous tocombine the storability and stability of solid fuels with the higherspecific impulse and controlability of liquid fuels. The hybrid fuels ofthis invention provide an improved fuel composition combining manyadvantages of both types of fuel.

Liquid fuels are used in combination with oxidizing agents, such as forexample liquid oxygen (LOX), red fuming nitric acid, etc. While thesecombinations yield high specific impulse, it is also known that if thedensity of the fuel is increased such as by the use of certaincombustible metals or metal compounds suspended in the fuels, and thesolid-liquid mixture is used in conjunction with the appropriateoxidizing agent, the combination yields a much higher specific impulse.In practice the use of such combinations presents problems since thesolid must be kept uniformly suspended in the liquid to obtainconsistent performance. Attempts have been made to suspend solids inliquids by increasing the viscosity of the liquids, for example by theuse of polymeric materials, but it was soon discovered that simplyincreasing the Newtonian viscosity of the liquid does not solve theproblem since the settling of the solid was only slowed and not actuallyprevented. It was found necessary to produce gels or thixotropiccompositions which under low shear behave like elastic solids and yet,under high shear, flow freely enough to be pumpable.

However, the use of gels only partly solved the problem. If a gel wasprepared which is stiff enough to suspend the solids, it was often toothick to pump. If a 3,352,109 Patented Nov. 14, 1967 gel was subjectedto high shear in pumping or in manufacture, it often permanently lostenough of its gelling action so that it allowed the solids to separate.Since gels are sticky, they do not flow from the fuel tanks cleanly, asmuch as a 10% hold up having been experienced. In addition, materialsused to produce gels are usually difficult to dissolve in the liquidfuel and gels sometimes become tender on ageing. Furthermore thereproducibility of properties from batch to batch in gelled compositionsis often poor.

A further objection to the use of gels is the mechanism by which thesolids are held in suspension. Gels to be used in this type ofapplication must have yield points, that is they must require a definiteinitial shearing force before they begin to flow. When at rest theybehave like elastic solids and the suspended solids are trapped in thegel matrix. Once they begin to flow, however, or when the yield point isexceeded, the solids can begin to settle.

This invention produces a stiffened liquid fuel by an entirely differentmechanism. In the practice of this invention an emulsion is made of theprincipal liquid fuel in a small amount of a second combustible orvolatile but immiscible liquid. These emulsions are characterized byhaving a very low volume percent of external phase, and are highlythixotropic. Although they appear to be elastic solids, having much theconsistency of a gelatin gel when at rest, they can however be easilypumped under low pump pressures. Thus, they can be considered to behybrid fuels.

Furthermore, the present invention suspends solid particles by anentirely different mechanism. In the composition of this invention thesolid particles may be said to be encapsulated in the individualglobules of internal liquid phase. Thus, in order to settle they wouldhave to pass through a multiplicity of interfaces which they cannot dowithout breaking the emulsion. Therefore, as long as the emulsion isstable the solids remain suspended.

The hybrid fuels of this invention are high internal phase-low externalphase emulsions. They may be either oil-in-water and water-in-oil typeemulsions but preferably oil-in-water. The internal phase of theemulsion may be at least by volume, for example at least preferably atleast but can be at least by volume or greater, the residue of theemulsion comprising the external phase and the emulsifier.

A minor but sufficient amount of emulsifier is added to form theemulsion, for example from 0.055% by volume such as from 0.14%, butpreferably from 0.2- 3% of emulsifier, based on the volume of totalemulsion.

The emulsion has two phases, one of which is the non-aqueous or oilyphase and the other the aqueous or non-oily phase. Each phase must becombustible and/or volatile when employed as a jet or rocket fuel. Ingeneral, the oily phase may be any fuel suitable in a jet or rocket fuelsuch as for example a hydrocarbon fuel generally of petroleum origin.

The term oily phase, as herein employed, is intended to include a vastnumber of substances, both natural and artificial, possessing widelydifferent physical properties and chemical structures. All of thesubstances included within this term are practically insoluble in water,possess a characteristic greasy touch and have a low surface tension.These include the animal oils of both land and sea animals; vegetableoils, both drying and non-drying; petroleum or mineral oils of variousclasses, including those of open chain hydrocarbons, cyclic hydrocarbonsor cycloparaffins, with or without the presence of solid paraffins andasphalts and various complex compounds, and which may or may not containsulphur or nitrogenous bodies; resin oils and wood distillates includingthe distillates of turpentine, rosin spirits, pine oil, and

acetone oil; various oils, obtained from petroleum products, such asgasolenes, naphthas, gas fuel, lubricating and heavier oils; coaldistillate, including benzene, toluene, Xylene, solvent naphtha,creosote oil and anthracene oil and ethereal oils.

Furthermore, the presence of the usual amounts of anti-knock compoundsor other conventional fuel additives in the oil does not adverselyaffect the usefulness of the oil for our purposes.

The choice of oily phase materials is not limited to hydrocarbons sinceesters such as dibutyl phthalate, diethylmaleate, tricresylphosphate,acrylate or methacrylate esters, natural esters, and the like have beenemployed by us successfully in the preparation of useful emulsions. Tungoil, oiticica oil, castor oil, linseed oil, poppyseed oil, soyabean oil,animal and vegetable oils such as cottonseed oil, corn oil, fish oils,walnut oils, pineseed oils, olive oil, coconut oil, degras, and thelike, may also be used.

Practically, the choice of a liquid hydrocarbon for use in a rocket orjet engine is based largely on availability and cost, and on this basisa petroleum hydrocarbon in the gasoline-kerosene range is the preferredmaterial. Generally either liquid oxygen or fuming nitric acid is usedwith it as the oxidizer. Whenever the latter is used, practically all ofthe nitrogen in the acid, under proper burning conditions; appears inthe combustion products as nitrogen gas. Aliphatic hydrocarbons frompetroleum (gasoline, kerosene) are the cheapest and most abundant liquidfuels for rockets. The simpler aromatic hydrocarbons (benzene, toluene)are also abundant, have higher densities, and in general give morethermal energy per pound on combustion so that they produce somewhatmore thrust per pound of fuel. Aliphatic hydrocarbons, from thestandpoint of structure and heat of combustion, could be expected not todifier appreciably one from another in the energy they could contributeto a jet motor. Unsaturated hydrocarbons which are endothermic (that is,which have negative heats of formation) will, of course, liberate thisheat during combustion and contribute to higher exhaust velocities. Thehighest calculated value of specific impulse for a hydrocarbon burnedwith oxygen is for diacetylene, HCECCECH, which gives 271 pound-secondsper pound. This is the highest that can be expected from anycarbonaceous fuel burned with liquid oxygen at 300 p.s.i.a. A more usualvalue (that for normal octane) is about 240 poundseconds per pound.

The aqueous phase is generally water or another substance suitable forthe fuel which is immiscible in the oily phase, for example water, analkyleneetherglycol such as diethylene glycol, etc.

The emulsions of the present invention possess the following advantages:

(1) Nonadhesive-They tend not to stick to the sides of the container.Thus hold up in fuel tanks is minimized.

(2) Visc0sity.The apparent rest viscosity is greater than 1000 cps.,generally in the range of l0,000100,000 or greater. However, under lowshear, they will flow with a viscosity approaching that of the liquidphases. On removal of shear, the recovery to original apparent restviscosity is nearly instantaneous. The hysteresis loop is very small.

(3) Temperature stability.Increased temperature has little effect onviscosity until the critical stability temperature is reached at whichthe points emulsions breaks into its liquid components. This permits awide temperature range of operation.

(4) Shear stability.-Emulsions may be subjected repeatedly to shearwithout degradation so long as the critical shear point is not reached.At this point the emulsion breaks. However, the critical shear point issufiiciently high to permit pumping at high rates.

(5) Quality c0ntroI.With these emulsions it is easy to reproduce batcheswith identical properties due to the absence of any "gel structure.

(6) Metering, heat transfer, and nozzle spray characteristics.-Sinceemulsions can be broken with high shear, this can be done at theturbopump, giving completely liquid flow from that point on. This willpermit metering by conventional means and will preclude laminar flowwith attendant reduction of heat transfer capability, resulting incompletely liquid nozzle flow and combustion characteristics.

(7) Solid 10ading.-Emulsions will flow well even with high solidsloading since they have a broad range between rest viscosity andviscosity under modest shear.

In contrast to very high volume percent solid loading in gels orslurries which result in a putty, these emulsions can suspend suchsolids in the internal phase while allowing the external phase to governfiowability.

(8) Recovery of oily pl1ase.-When gelling agents are dissolved in thefuel, distillation is required to recover the original component. Withemulsions, application of high shear or high temperature to break theemulsion, and a subsequently decantation or drawoff operation, is allthat is required. This is significant in considering a storable weaponsystem. It would be a simple matter to exhaust a missile, break the fuelemulsion, and remake it periodically as required.

Any suitable emulsifier can be employed. The emulsifiers most usuallyemployed in the practice of this invention are generaly known asoxyalkylated surfactants or more specifically polyalkylene ether orpolyoxyalkylene surfactants. Oxyalkylated surfactants as a class areWell known. The possible sub-classes and specific species are legion.The methods employed for the preparation of such oxyalkylatedsurfactants are also too well known to require much elaboration. Most ofthese surfactants contain, in at least one place in the molecule andoften in several places, an alkanol or a polyglycolether chain. Theseare most commonly derived by reacting a starting molecule, possessingone or more oxyalkylatable reactive groups, with an alkylene oxide suchas ethylene oxide, propylene oxide, butylene oxide, or higher oxides,epichlorohydrin, etc. However, they may be obtained by other methodssuch as shown in US. Patents 2,588,771 and 2,596,091-3, or byesterification or amidification with an oxyalkylated material, etc.Mixtures of oxides may be used as well as successive addition-s of thesame or different oxides may be employed. Any oxyalkylatable materialmay be employed. As typical starting materials may be mentioned alkylphenols, phenolic resins, alcohols, glyeols, amines, organic acids,carbohydrates, mercaptans, and partial esters of polybasic acids. Ingeneral, the art teaches that, if the starting material iswater-soluble, it may be converted into an oil-soluble surfactant by theaddition of polypropoxy or polybutoxy chains. If the starting materialis oil-soluble, it may be converted into a water-soluble surfactant bythe addition of polyethoxy chains. Subsequent additions of ethoxy unitsto the chains tend to increase the water solubility, while, subsequentadditions of high alkoxy chains tend to increase the oil solubility. Ingeneral, the final solubility and surfactant properties are a result ofa balance between the oil-soluble and watersoluble portions of themolecule.

In the practice of this invention it has been found that emulsifierssuitable for the preparation of high internal phase ratio emulsions maybe prepared from a wide variety of starting materials. For instance, ifone begins with an oil-soluble material such as a phenol or a long chainfatty alcohol and prepare a series of products by reaction withsuccessive portions of ethylene oxide, one finds that the members of theseries are successively more watersoluble. One finds also that somewherein the series there will be a limited range where the products areuseful for the practice of this invention. Similarly it is possible tostart with water or a water-soluble material such as polyethylene glycoland add, successively, portions of propylene oxide. The members of thisseries will be progressively less water-soluble and more oil-soluble.Again there will be a limited range where the materials are useful forthe practice of this invention.

In general, the compounds which would be selected for testing as totheir suitability are oxyalkylated surfactants of the general formulawherein Z is the oxyalkylatable material, R is the radical derived fromthe alkylene oxide which can be, for example, ethylene, propylene,butylene, epichlorohydrin and the like, It is a number determined by themoles of alkylene oxide reacted, for example 1 to 2000 or more and m isa whole number determined by the number of reactive oxyalkylatablegroups. Where only one group is oxyalkylatable as in the case of amonofunctional phenol or alcohol ROH, then m =1. Where Z is water, or aglycol, m=2. Where Z is glycerol, m=3, etc.

In certain cases, it is advantageous to react alkylene oxides with theoxyalkylatable material in a random fashion so as to form a randomcopolymer on the oxyalkylene chain, i.e. the [(OR), OH] chain such asAABAAABBABABBABBA- In addition, the alkylene oxides can be reacted in analternate fashion to form block copolymers on the chain, for exampleBBBAAABBBAAAABBBB or BBBBAAACCCAAAABBBB where A is the unit derived fromone alkylene oxide, for example ethylene oxide, and B is the unitderived from a second alkylene oxide, for example propylene oxide, and Cis the unit derived from a third alkylene oxide, for example, butyleneoxide, etc. Thus, these compounds include terpolymers or highercopolymers polymerized randomly or in a block-Wise fashion or manyvariations of sequential additions.

Thus, (OR) in the above formula can be written -A B C or any variationthereof, wherein a, b, and c are or a number provided that at least oneof them is greater than 0.

It cannot be overemphasized that the nature of the oxyalkylatablestarting material used in the preparation of the emulsifier is notcritical. Any species of such material can be employed. By properadditions of alkylene oxides, this starting material can be renderedsuitable as an emulsifier and its suitability can be evaluated byplotting the oxyalkyl content of said surfactant versus its performance,based on the ratio of the oil to water which can be satisfactorilyincorporated into Water as a stable emulsion. By means of such a testingsystem any oxyalkylated material can be evaluated and its properoxyalkylation content determined.

As is quite evident, new oxyalkylated materials will be constantlydeveloped which could be useful in our compositions. It is therefore notonly impossible to attempt a comprehensive catalogue of suchcompositions, but to attempt to describe the invention in its broaderaspects in terms of specific chemical names of its components used wouldbe too voluminous and unnecessary since one skilled in the art could byfollowing the testing procedures described herein select the properagent. This invention lies in the use of suitable oxyalkylatedemulsifiers in preparing the compositions of this invention and theirindividual composition is important only in the sense that theirproperties can effect these emulsions. To precisely define each specificoxyalkylated surfactant useful as an emulsifier in light of the presentdisclosure would merely call for chemical knowledge within the skill ofthe art in a manner analogous to a mechanical engineer who prescribes inthe construction of a machine the proper materials and the properdimensions thereof. From the description in this specification and withthe knowledge of a chemist, one will know or deduct with confidence theapplicability of oxyalkylated emulsifiers suitable for this invention bymeans of the evaluation tests set forth herein. In analogy to the caseof a machine wherein the use of certain materials of construction ordimensions of parts would lead to no practical useful result, variousmaterials will be rejected as inapplicable where others would beoperative. One can obviously assume that no one will wish to make auseless composition or will be misled because it is possible to misapplythe teachings of the present disclosure in order to do so. Thus, anyoxyalkylated surfactant that can perform the function stated herein canbe employed.

REPRESENTATIVE EXAMPLES OF Z No. Z

2 Rn O- O 5 BAL -1i- 0 6 R( i-N H 7 Rl I-' 8 ltN 9 Phenol-aldehyderesins.

1O O (Ex.:Alkylene oxide block polymers.)

O X= -O, S, CH:g etc.

0 12 RS-CHi( 3O 13 RPO|H- 14 RPO4 H 16 Rn- SO2I I 17 Rug-sons:

O H 18 R ii N 19 Polyol-derived. (Ex.: Glycerol, glucose,pentaerythritol.) 20 Anhydrohexitan or anhydrohexlde derived. (Spans andTweeus.)

21 Polycarboxylic derived.

22 CHCHr-On amine Examples of oxyalkylatable materials derived from theabove radicals are legion and these, as well as other oxyalkylatablematerials, are known to the art. A good source of such oxy alkylatablematerials, as well as others, can be found in Surface Active Agents andDetergents, vol. 1 and 2, by Schwartz, et al., Interscience Publishers(vol. 1, 1949-vol. 2, 1958) and the patents and references referred totherein.

In general, the base oxyalkylatable material is tested for solubility inwater or toluene, or any other suitable oily material. If it is watersoluble it is oxyalkylated with propylene or butylene oxide until it isjust oil soluble, with representative samples being collected as itsoxyalkylate content is increased. If the oxyalkylatable material isoilsoluble, then it is oxyalkylated with ethylene oxide until it is justwater-soluble, with representative samples being collected as itsoxypropylation or oxybutylation content is increased. These samples aresimilarly tested. This procedure can thereupon be repeated with anotheralkylene oxide until opposite solubility is achieved, i.e. if thematerial is water-soluble it is oxypropylated or oxybutylated until itis oil-soluble. If the prior oxypropylated or oxybutylated material isoil-soluble, it is treated with ethylene oxide until it iswater-soluble. This can be repeated in stages each time changing thematerial to one of opposite solubility by using a hydrophile oxide (i.e.EtO) for an oil-soluble material and a hydrophobe oxide (i.e. PrO orBuO) for water solubility. The same procedure and tests are employed ateach stage, proceeding each time to oxylation to opposite solubility.

Although the amount of oxyalkylated material present in the emulsion hasbeen stated to be 0.05-5 volume percent, but preferably 0.23%, largeramounts can also be employed if desired. However, economics generallyrestrict the amount employed to the ranges indicated.

The exact range which is useful for the practice of this invention willvary with the starting emulsifier base and the sequence of alkyleneoxides used to achieve the polyalkylene ether chains. It should also benoted that materials useful in the practice of this invention can bemade by other Well-known methods besides oxyalkylation such as theesterification of a polyalkylene ether alcohol, reaction of carboxylicacids with oxyalkylated amines, etc. Thus, the term oxyalkylatedincludes any means of attaching the oxyalkyl group to a molecule. Anymethod of attaching oxyalkyl groups to a molecule can be employed.

It has also been found that the optimum range of effectiveness for anyparticular emulsifier series will vary with the particular oil phase andalso with the composition of the aqueous phase which is employed.

To illustrate the variety of materials that may be used as emulsifiersin the practice of this invention the follow ing examples are presented.It should be noted that these examples are simply illustrative andshould not be construed as imposing limitations on the scope of theinvention.

Example 1 The same general procedure was employed as described in U.S.Patent 2,572,886, Example la, columns 9 and 10, except that the startingmaterial was n-decanol. Propylene oxide was added first in a weightratio of 1.96 parts of oxide to one part of n-decanol, and ethyleneoxide was then added in a ratio of 2.61 parts of oxide to one part ofn-decanol. The final product was a viscous amber liquid.

Examples 2 through 8 were prepared in the same mannet as Example 1except that the relative amounts of n-decanol, propyleneoxide, andethylene oxide added in the order given were as listed in Table I.

TABLE I Weight Whip ht \Volght Example No. u-ticeanul Prom leuo Lthylune()xidc Oxide In Table II a series of examples are given in which a crudeaikyl (C C phenol was treated with ethylene oxide in the method ofExample 1.

TABLE II One part by weight of crude phenol foots was reacted with theparts shown in the table of ethylene oxide.

Examples 22 through 33 were made by the same general method described inExample 1 except that the starting material was glycerine. Theproportions of reactants are listed in Table III. The alkylene oxideswere added in the order given reading from left to right.

TABLE III One part by weight glycerine t0- Ex. .\'o.

Parts Ethylene Oxide 1 But ylune tit-tile 1S Propylene Oxide Example 34Amixed nonyl-butyl phenol-acid catalyzed-formaldehyde resin was preparedby the method of US. Patent 2,499,370, Example la.

Examples 35 through 48 were prepared by stepwise oxyalkylation of theresin produced in Example 34 by the procedure described in US. Patent2,499,370, Example 1b, except that the proportions of oxides used wereas listed in Table IV. The oxides used were as listed in Table IV. Theoxides were added in the order given reading from left to right.

TABLE IV Moles of Propylene Oxide Moles of Ethylene Oxide Ex. No. perphenolic unit of per phenolic unit of starting resin starting resin 1,012 150.8 1,012 246.1 1,012 336. 5 1, 012 449. l, 012 581. 0 1,012 893.71, 012 1, 343. 0 848 129. l 848 199. 3 848 285.0 848 376. 1 848 487. 5848 756. O 848 1, 147. 8

Examples 49, 50, 5]

Polyepichlorohydrin-amine compounds were prepared by the methodsdescribed in application 820,116, filed June 15, 1959, and assigned toPetrolite Corporation, De Groote and Cheng.

Example 49 is Example 18b of said application. Example 50 is Example 19bof said application. Example 51 is Example 17b of said application.

Example 52 The product of Example 49 was treated as in Example 1 exceptthat the starting material was treated with 2.16 parts of propyleneoxide, 3.31 parts of ethylene oxide and finally with 19.6 parts ofpropylene oxide in the order given.

Example 53 The product of Example 50 was treated as in Example 1 exceptthat 2.24 parts of propylene oxide, 2.85 parts of ethylene oxide, and24.3 parts of propylene oxide were used in the order given.

Example 54 TABLE V Starting Material Product of Percent AdditionalEthylene Oxide Based Example No.

on Starting Material Example 66 The procedure of Example 1 was employedexcept that 1.3-butanediol was the starting material and 3.0 parts ofbutylene oxide, 32.2 parts of propylene oxide, and 16.6 parts ofethylene oxide were employed in the order given.

Example 67 The general procedure of Example 1 was employed except thatthe starting material was triethylene glycol and that 5.1 parts ofbutylene oxide, 30.0 parts of propylene oxide, and 22 parts of ethyleneoxide were used in the order given.

10 Example 68 The same general procedure as Example 1 was employedexcept that the starting material was tetraethylene glycol and that 5.1parts of butylene oxide, 30.0 parts of propylene oxide, and 14.0 partsof ethylene oxide were used in the order given.

Example 69 One part of dipropylene glycol was treated with 29.8 parts ofpropylene oxide and 20.5 parts of ethylene oxide in this order accordingto the general procedure of Example 1.

Example 70 One part by weight of castor oil was treated with 6.8 partsof propylene oxide according to the procedures mentioned above.

Example 71 One part by weight of crude tall oil was treated with 3.27parts of ethylene oxide according to the procedures mentioned above.

Example 72 One mole of stearyl alcohol was treated with 3.12 moles ofethylene oxide and then the resulting material was reacted with 1.5moles sulfamic acid to convert the terminal hydroxide to a sulfategroup.

Example 73 181 grams of a mixture of C to C fatty acids were heated in areaction flask with 61 grams of monoethanob amine. The result was aviscous brown material which consisted for the most part of amides ofthe mixed acids.

One of the new and novel aspects of the present invention is the easewith which the emulsions can be prepared. While a few instances ofemulsions of over 70 to 75% internal phase have been known to the art,they are difiicult to prepare and tend to be unstable. Most of them arelaboratory curiosities and not well adapted to large-scale, commercialproduction.

Present practice for the commercial production of emulsions of evenmoderately high internal phase ratio calls for the use of a colloid millor other method of extremely high shear. Paint mills, high speed conemills, and roller mills are employed. These methods require the use ofexpensive equipment and the utilization of large amounts of power. Evenwith these methods, the internal phase ratio seldom exceeds 70% internalphase.

On the contrary, in the practice of this invention only the simplestequipment is required. Actually useful and novel emulsions with internalphase ratios of over and even over and to 99%, can be made by simplehand stirring with a paddle or spoon. In actual practice a wide varietyof mixing devices may be used. The following examples will illustratethe great advantages to be gained by the practice of this invention. Theexamples should not be construed as limitations on the methods which maybe employed.

Example 74 Ten ml. of water and 2 ml. of the material of Example 1 weremixed by shaking in a quart jar. Ten ml. of isooctane was added and themixture shaken until all the isooctane had emulsified. Additionalamounts of isooctane were added, with shaking, until a total of 800 ml,of isooctane had been added. The result was a still", almost translucentjelly. This material was found to be stable over the range 10 C. to 50C. for several weeks. It is an oil-in-water emulsion as shown by thefact that it can be diluted with water to form a thin, white dispersionof isooctane in water.

Example 75 Three quarts of water and 150 ml. of the material of Example66 were thoroughly mixed. One gallon of kerosene was then added andmixed into this material until a smooth emulsion was formed. This premixwas then placed into a 20 gallon open mixing vessel, equipped with ananchor type stirrer. With the stirrer revolving at about 200 r.p.m.,additional kerosene was added until a total of ten gallons of kerosenehad been mixed in. The result was a white, highly thixotropic,oil-in-water emulsion. Samples of this material were stable after beingstored in closed containers for ten months at normal room temperature.

Example 76 A two inch diameter, Viking pump, driven by an electric motorat 850 rpm, was equipped with an eight foot flexible hose on the outletand a similar flexible hose on the inlet. The ends of the two hoses wereplaced in a 50 gallon, open head, steel drum. With this arrangement,material could be pumped out of the drum, through the pump, and backinto the drum.

One gallon of water and one pint of the material of Example 67 weremixed together and placed in the steel drum. While this material wascirculated by the pump, mineral spirits was slowly added to the intakeof the pump. In about 15 minutes, 50 gallons of mineral spirits had beenadded and the result was a thick, white, jellylike emulsion.

For the preparation of small laboratory batches of emulsions it ispreferred to use a kitchen-type mixer, such as the model C3, Kitchen AidMixer manufactured by the Hobart Manufacturing Company. This mixer usesa two quart glass mixing bowl and a wire beater with a planetary motion.The testing procedure is as follows:

Example 77 Ten ml. of the aqueous phase is mixed with a suitable amount,usually 2 ml. to 4 ml., of the emulsifier in a glass mixer bowl. Withthe mixer running at a speed setting of 2 to 6, the organic phase isslowly added to the bowl. Initial additions should be made in smallamounts, allowing the mixer ample time to incorporate the oil into theemulsion. As the amount of material in the bowl increases, the mixingaction is more efficient and further additions may be made more rapidly.When the mixer will no longer produce an emulsion with no free oilphase, the limit of the test is considered to have been reached.

In general, it has been found that emulsifiers which have heretoforebeen used for the production of conventional oil-in-water emulsions willnot permit the incorporation of more than 20 to 30 ml. of oil phasebefore breaking or inversion occurs. On the contrary, the materials ofthis invention allow the incorporation of over 100 ml. of oil phase intoa stable emulsion and it is quite common to incorporate 500 ml. or moreof oil phase. In fact, a material suitable is not usually considered forpractical use if it does not permit the incorporation of at least 450ml. of the oil phase per 10 ml. of non-aqueous phase.

As stated above, a wide variety of materials may be used as emulsifiersin the practice of this invention. However, not all materials of aparticular type are suitable for the production of a specific emulsion.As previously stated, the effectiveness of a particular material varieswith the composition of both the oil and aqueous phase. One finds thatthe test outlined in Example 77 a simple and convenient method ofestablishing the optimum material for a particular system. Table VIshows the amounts of oil phase which may be successfully incorporatedinto 13 ml. of the aqueous emulsifier mixture by the procedure ofExample 77.

TABLE \'I Ml. of Kerosene in Example No. phase plus 3 ml. of I phase ofemulsion eillLllSll'ltt None None None None None '\'o1ie lono None I043. 5

20 til). ti

It will be noted that the emulsifiers listed in Table VI representmembers of a family of related materials produced by the reaction ofsuccessively greater amounts of ethylene oxide with a phenol. Thecomposition of all possible members of this family may be represented ina one-dimensional, i.e. straight line, diagram. The base line of FIGURE1 represents such a one-dimensional composition space. In FIGURE l, thedata of Table VI has been plotted in a conventional manner upon the baseline. It will be noted that the effectiveness of the materials in thisparticular system definitely passes through a maximum as one travelsalong the base line in the direction of increased ethylene oxidecontent.

In a similar manner it will be noted that the materials of Examples 1through 8 are members of a general family prepared by the stepwiseaddition of first propylene oxide and then ethylene oxide to n-decanol.All possible members of this family may be plotted in a twodimensionalcomposition space where the origin represents the parent alcohol, onedimension represents successively larger amounts of propylene oxide, andthe other dimension represents successively larger amounts of ethyleneoxide, added to the base alcohol, in this case n-decanol. (1) in thediagram represents first addition, {2) second addition. FIGURE 2illustrates this method of plotting the compositions of Examples 1through 8. It should be carefully noted that this composition space isnon-commutative. That is, it makes a real difference if the ethyleneoxide is added before the propylene oxide. FIGURE 2, as represented, isvalid only if all the propylene oxide is added before the ethylene oxideis added. Stated another way-oxyalkylatable base plus ethylene oxideplus propylene oxide does not equal base plus propylene oxide plusethylene oxide. That is, of course, implicit in the statement that thecomposition space is non-commutative.

Table Vll records the amounts of hydrocarbon that may be successfullyincorporated into a stable oil-in-vvater emulsion according to themethod of Example 77.

TABLE VII Emulsifier of example No; Ml. l 620 2 270 3 None 4 230 5 480 6650 7' 600 8 500 Milliliters of hydrocarbon emulsified in 10 ml. ofwater by 3 ml. of emulsifier.

In FIGURE 2 the data of Table VII is plotted on the non-commutativecomposition space discussed previously by letting the size of thecircles represent the milliliters of internal phase that can beincorporated into a stable emulsion and the location of the centers ofthe circles represent the composition of the emulsifier. Obviously, fora complete delineation of the maximal performance area considerably morepoints would have to be obtained. Even with these few points, however,it is possible to begin to see the location of areas of superiorperformance. It is also obvious that this technique of assembling thedata on the model of a composition space brings related materials intoconjunction and makes it possible to analyze the data for the selectionof compounds with maximum effectiveness.

It is interesting to note that, while the material of Example 2 has someeffectiveness as an emulsifier, the effect of the addition of a smallamount of ethylene oxide to this compound to form Example 3 is todestroy the effectiveness. Further additions of ethylene oxide toproduce the materials of Examples 4 through 7 unexpectedly result in theproduction of materials with progressively increased effectiveness,reaching a maximum in Example 6. It would obviously be impossible topredict such behavior from the present teaching of the art.

In general, in the practice of this invention, the preferred method forselection of materials of optimum effectiveness is to prepare a familyof related materials and test them for effectiveness in the particularaqueous-oil system that is under consideration. A water-soluble base isoxyalkylated with propylene oxide (PrO) or butylene oxide (BuO) until itjust becomes oil-soluble and selected members of the series are tested.An oil-soluble base is treated with ethylene oxide (EtO) and similarlytested. A test such as that outlined in Example 77 may be used or anyother test that accurately reflects the proposed methods of preparationof the desired emulsion. The results of the tests are then plotted on amultidimensional non-commutative composition space that represents thefamily of materials being used. Such tests and plots reveal theexistence of an optimum-performance region in the composition space.

A full discussion of devices of this type can be found in US. Patent3,083,232.

Table VIII shows the results of a series of tests such as those ofExample 77 which were run on the materials of Examples 35 through 48.FIGURE 3 shows the results of Table VIII plotted on a composition-spacediagram.

TABLE VIII Emulsifier of example No.: M1. 35 None 36 None 37 295 38 42039 280 40 400 41 250 42 43 20 44 20 45 334 46 350 47 310 48 Millilitersof oil phase incorporated into stable emulsion in 10 ml. of Water and 3m1. of emulsifier by stirring in mixer bowl at speed No. 2.

Here again, as in FIGURE 2, the great advantage of the composition-spaceplot is apparent.

Table IX records the results of a series of tests for optimum efficiencywhich were run on the family of materials represented by Examplesthrough 31. These materials were prepared by three separate stepwiseadditions of different alkylene oxides. Specifically they were preparedby reacting glycerine with, first, butylene oxide; second, propyleneoxide; and lastly with ethylene oxide. This family of materials may berepresented in a three dimensional, non-commutative, composition space.This is an obvious extension of the method of the previousone-dimensional and two-dimensional examples. A sketch of such athree-dimensional, composition space is shown in FIGURE 4. The threestraight lines passing vertically through the composition spacerepresent sub-families of the general class, the members of which differonly in the amount of final ethylene oxide which Was added. FIG- URES 4,5, 6, and 7 show the relative effectiveness of these sub-families asrecorded in Table IX. Again inspection of the three line graphs andtheir inter-relation as represented in FIGURE 4, make it possible todefine regions of maximum efiiciency in the three-dimensionalcomposition spaced. This can act as a valuable guide in the furtherexploration of the regions and in the selection of the best material forcommercial exploitation.

1 Milliliters of oil phase attained in emulsificatiion test.

A similar series of test results is recorded in Table X for thematerials of Examples 49 through 65. These materials are members of arather complex family of materials. The synthesis may be considered tohave five distinct steps.

TABLE X Emulsifier of Example N o. M 1. Relative emulsifiedeffectiveness 200 Not stable. 250 Stable emulsion. 300 D0. 280 Notstable. Stable emulsion. Do. 340 Not stable. 290 D0. 330 Do. 300 D0.

30 Stable emulsion. 350 Do. 220 D0. 450 D0. 300 D0. 250 Do. 480 D0.

These steps consist of the original polymerization of epichlorohydrinand the condensation With the polyamine, the treatment with propyleneoxide, then with ethylene oxide, then again with propylene oxide, andfinally again with ethylene oxide. Examples 49, 50, and 51 representmaterials taken at the end of step one. Examples 52, 53, and 54represent materials taken at the end of step four. The rest of theexamples of the group represent materials obtained by performance of thefinal step in the series. By a direct extension of the mappingprinciples outlined in the previous discussion using standardmathematical techniques, the materials of this series may be regarded asbeing distributed within a five-dimensional non-commutativecomposition-space. Mapping of suitable twoand three-dimensional regionsof this composition space serve to delineate the maximal regions. Thenumber of twodimensional and three-dimensional maps required to demarkthe region fully is, naturalfy, larger than for the simplerlower-dimensional examples. For brevity, only a schematic plot and aprovisional plot of the last two dimensions is given in FIGURES 8 and 9.

It should be noted in passing that if only Examples 52, 55, 56, 57 and58 of this group had been tested, the family would have been rejected asunsuited for the purposes of the invention. The selection of otherregions in the composition-space, however, reveals materials ofpotential utility.

Other materials of a non-oily nature are also used as jet and rocketfuels. Examples of such fuels are ethyl and methyl alcohols, pyridine,pentaborane, dihydropenlaborane, aluminum borohydride, etc. If suchnon-oily fuels are to be primary liquid fuel for a system, a nonmiscibleoily phase must be chosen for the minor component, external phase of theemulsion. In general, any nonmiscible liquid may be chosen provided thatit is nonreactive with the principal fuel, is combustible or volatile,and is compatible with the emulsifier. In general the choice of theexternal phase is dictated by solubility properties and potential fuelvalue. These are examples of non-oily type emulsions, i.e., oil externalemulsions and aqueous to the watenin-oil type emulsions.

The final viscosity of these compositions is a function of theparticular emulsifier used, the ratio of the two phases, and the methodemployed to produce the intimate mixture. Compositions may be formedwhich vary in consistency from that of thick cream to jellies which areso stiff that they may be cut into pieces and stand unsupported. Thus,the viscosity may be chosen to suit the particular application. Forexample, a series of compositions were made as described in Example 77in which successively larger amounts of hydrocarbon were mixed into theemulsion. With 200 ml. of oil phase the viscosity as measured with aBrookfield viscometer, using a No. 4 spindle at 6 r.p.m., was 58,000 cp.When 300 ml. of oil was used the viscosity was 85,000 cp. and when 600ml. of oil was used the viscosity was over 100,000 cp. All of thesecompositions are thixotropic, i.e. the measured viscosity is a functionof the rate of shear. For exampfe, the case cited above, using 200 ml.,showed a viscosity of 58 cp. at 6 r.p.m. The viscosities at 12 r.p.m.,30 r.p.m., and 60 r.p.m. respectively were 29,500, 13,800, and 8,000.Thus, as the rate of shear increases the effective viscosity decreases.This is of great importance where the material has to be pumped. Itmeans that a material that, when stationary or at low shear, behaveslike a thick jelly, will become fluid while being pumped and regain itsviscosity as it slows down. This thixotropy is a general property of thecomposition of this invention.

Illustrations have already been given of the wide variety of materialsthat may be used as emulsifiers in the practice of this invention. Itshould be noted that no single specific emulsifier will necessarily beoperative on all possible phase combinations. However, by theapplication of a simple laboratory test such as that outlined in Example77, anyone skilled in the art can readily ascertain the emulsifier bestsuited for any particular purpose.

It has been shown that the phase ratio has an effect on the finalviscosity of compositions. The particular emulsi fier also has aneffect. For example, three compositions were made by the general methodof Example 77, using 200 ml. of kerosene as the oil phase and thematerials of Examples 18, 1, and 67 as emulsifiers. The viscosity of thecompositions as measured with a No. 4 spindle at 6 r.p.m. was 58,000,32,000, and 26,000 respectively. Thus, it can be seen that the controlof the final properties of the compositions may be effected by thechoice of emulsifier.

The method of making the emulsions will also have a profound effect onthe final viscosity of the com-position. For example two batches ofmaterial were made by the method of Example 77 using kerosene as theinternal phase and water as the external phase, with the material 16 ofExample 67 as the emulsifier. The only difference in the operation wasthat one batch was allowed to stir for 5 minutes after all trace of freekerosene had disappeared. The least stirred material had a viscosity of26,000 cp. The material which had been stirred longer had a viscosity ofover 100,000 cp, Thus, it will often be found that by continuing thestirring for a longer period than necessary to form a stable emulsionwill often result in a more viscous product. Contrary to generalemulsion practice, however, increased shear, will not necessarily make astiffer composition. In fact, if a method employing extremely high shearis used, an inferior emulsion results. For example, in the method ofExample 77 it is often easier to get a satisfactory emulsion by usingthe low speeds on mixer than it is using high speeds. It is as thoughthe higher shear methods prevent the formation of the necessarystructure in the composition and may even cause inversion. As a furtherexample may be mentioned the use of pumps as mixers as outlined inExample 76. It has been found that a moderate speed pump with someslippage such as a Jabsco pump with a fiexible rubber impeller or aViking pump perform well. However, it is found that if the speed of thepump is increased the effectiveness increases to a point and then fallsoff sharply. In fact, these emulsions may be broken back to theircomponent phases by subjecting them to extremely high shear such as bypassing them through a high speed centrifugal pump or forcing themthrough a small nozzle. It is one of the advantages of this inventionthat high speed, high power equipment is not necessary for theproduction of these products. Colloid mills and other high shear devicesmay be eliminated and simple mixing and blending apparatus or pumps usedinstead. In field use such emulsions may be made by stirring with awooden paddle by hand.

In some applications it may be desirable to be able to break theemulsion and reclaim the original phases. In such cases advantage may betaken of the effect of extremely high shear. For instance, thickenedfuels of the type encompassed by this invention are easier to transportand less subject to evaporation, ignition, and spillage than fuels inconventional form. Due to their thixotropy they may be pumped withoutdifliculty. They may be broken back to the original fuel by passingthrough a nozzle and allowing the small amount of aqueous phase tosettle out. This is not true of gels which have been made from soaps andother materials currently used for such purposes.

Fuels prepared by the practice of this invention also have utility inapplications where the sloshing of fuels in storage tanks is a problem.Since the fuels are pumpable and yet viscous they may be used in liquidfuel rockets and jets. where the shift of weight concomitant with asudden change in direction will seriously affect the trim of the vessel.The reduced tendency to splash and shift lessens the need for elaboratebulkheads and allows more payload.

In summary, the emulsions of this invention have an apparent restviscosity of about 1,000 to 100,000 or more cps. such as 25,000 to100,000 or more, for example, 10,000-100,000, but preferably50,000l00,000 cps. Emulsions have been prepared having apparent restviscosities of about 10,000, 20,000, 30,000, 40,000, 50,000, 60,000,70,000 80,000, 90,000, 100,000 or greater.

The preferred embodiment of this invention comprises an emulsionconsisting of a minor amount of an external phase and a major amount ofan internal phase having a finely divided combustible solid dispersedwithin it. The choice of the solid is dictated primarily by specificimpulse considerations. The usual practice of this invention would be toselect a combination of liquid fuels and finely divided solids which aremutually non-reactive at storage temperatures and which yieldpotentially the maximum specific impulse. Specific impulse can bedefined by the following equation.

The expression for specific impulse (I and the equa- I =Specificimpulse, pounds of thrust per pound weight of propellant burned persecond.

F =Thrust, lb.

t=Duration of thrust due to burning, sec.

W=Total weight of propellant, lb.

m=Weight of propellant burned per second, lb./sec.

c=Effective exhaust velocity of propellant gases, ft./sec. (actualexhaust velocity of propellant gases in the case of rockets (but not forair-breathing jets), ft./sec.).

g=Acceleration due to gravity, ft./sec.

R'=RM=Universal gas constant, 1544 ft.-lb./(lb.-mole) R=Gas constant perpound weight of propellant gases,

ft.-lb./(1b.)( F.).

T =Cornbustion chamber temperature, R.

M =Average molecular weight of propellant gases.

C =Heat capacity of propellant gases at constant pressure, B.t.u./(lb.)F.).

C =Heat capacity of propellant gases at constant volume,

B.t.u./(lb.) F.).

P =Pressure of propellant gases at nozzle exit, p.s.i.

P =Pressure of propellant gases in combustion chamber,

where:

Having selected the best available combination fuels and solids andhaving calculated the optimum proportion of solids and fuel to be used,one selects a liquid for the external phase that is non-reactive witheither the fuel or the finely divided solid is immiscible with the fueland not a solvent for the solid fuel. Using the methods detailedelsewhere in these specifications, one then selects an appropriateemulsifier for the system. This emulsifier is then dissolved ordispersed in the external phase liquid and the mixture of solid andliquid fuels mixed into this liquid by any of the methods elsewheredescribed.

Examples of combustible solids elements which are of interest whencombined with appropriate liquid fuels are lithium, beryllium, boron,carbon, sodium, magnesium, aluminum, silicon, etc. The hydrides ornitrides of the above elements, when they are solids, may be employed.These are employed as finely divided solids, for example a particle sizeof less than about 200 microns, such as less than about 100 microns, forexample from about 0.5 to 50 microns, but preferably from about 1 tomicrons.

The amount of finely divided solids added to the fuel can vary widely,such as from about 5 to 200 g. or more per 100 volumes of emulsions, forexample from about 10 to 180, preferably from about to 140, but usuallyfrom about to 120.

The following examples are presented in non-limiting examples whichillustrate the practice of this invention which finely divided solidsare employed.

Example 78 To a 400 ml. beaker was added 10 ml. of water, 1 ml. of theemulsifier of Example 1, and 1 ml. of the product of Example 20 (TableH). These were mixed with a split disc stirrer driven by a Sergentstirrer motor until dissolved. Three hundred ml. of kerosene was thenadded slowly while stirring. The result was a smooth, white,

A similar emulsion was prepared in the manner of Example 78, except thatthe emulsifier of Example 18, Table II and 60 g. of carbon black wereemployed in place of g. of powdered aluminum.

Example 80 A similar emulsion was prepared in the manner of Example 78,employing g. of powdered aluminum except that the emulsifier of Example6, Table I, was employed.

Example 81 A similar emulsion was prepared in the manner of Example 78,employing 80 g. of powdered aluminum except that the emulsifier ofExample 40, Table IV, Wasv employed.

. Example 82 A similar emulsion was prepared in the manner of Example78, employing 80 g. of powdered aluminum except that the emulsifier ofExample 46, Table IV, was employed.

The above examples are employed to illustrate the preparation of theemulsions of this invention containing combustible powdered solids whichcan be employed in jet and rocket fuels. However, it should beunderstood that powdered aluminum and other powdered solids can besimilarly added to other emulsions prepared in accord with thisinvention, for example the emulsions described in the specific examplesdisclosed herein.

The emulsions of this invention can be employed in both mono-propellantand polypropellant systems. The emulsion can be employed to suspendedoxidizing agents in the fuel. For example, an inorganic oxidizing agentsuch as a nitrate or a perchlorate may be incorporated therein invarying amounts.

One can readily prepare emulsions containing about 20% by volume of suchoxidizers as nitrates, such as lithium nitrate, potassium nitrate, orhydrazine nitrate and the like, perchlorates, chlorates, chlorites,hypochlorites, dichromates, chromates and persulfates, such as thepotassium, sodium and ammonium salts. Salts of other metals such ascalcium, magnesium, aluminum and the like may also be employed.

The propellant mixture can comprise the fuel components containingfinely divided oxidizers in proportions preferably such that the fuel ispresent in molal excess, i.e., an excess in the amount which would beconsumed by the oxidizer in the propellant mixture would be from about50-90% of that which would be required for complete combustion of thefuel although when desired proportions of oxidizer above the 90% can beemployed, e.g.,

The oxidizers may be of the formula MA where M is the cation such as NH,or a metal and X represents the valency of M. The metal can be one ofthe metals of Group I-A, I-B, II-A, III-A, IV-A and VIII of the PeriodicTable of elements.

For example to use perchlorates as an example M(ClO the perchlorates canbe alkaline metal perchlorates such as the lithium, sodium, potassium,cesium, etc., perchlorates; magnesium, calcium, barium, iron, silver,thallium, etc., perchlorates.

Little is to be gained by a detailed description of the jet and rocketengines in which compositions of this type are burned. Recent details ofthe construction of such engines are not generally available due tosecurity restrictions. A general description of the operation of rocketand jet engines is given in Encyclopedia of Chemica: Technology,published by Interscience Publishers 1951), vol. 6, pages 954-959 underJet Propulsion Fuels and in vol. 11, pages 760-778 under RocketPropellants.

A short description of the operation of jet engines is given in the samepublication on page 954, and of rocket engines on pages 766-767 thereofand elsewhere. Since the compositions of this invention may be pumpedand handled in the same manner as liquids they are used in the sametypes of engines as conventional liquid fuels. They possess the uniqueadvantages of high density (due to the incorporated solids), stability,restartability, and high specific impulse.

Having thus described by invention, what I claim as new and desire toobtain by Letters Patent is:

1. A jet and rocket thixotropic hydrocarbon-in-water emulsion fuelcomprising (1) water, (2) an emulsifiable hydrocarbon, and (3) anemulsifying agent, said hydrocarbon being present in said emulsion fuelin an amount of at least 80% hydrocarbon by volume of the emulsion, saidemulsion having the characteristics of a solid fuel when at rest and thecharacteristics of a liquid fuel when a force is exerted on it, saidemulsion tending to be nonadhesive, said emulsion having a criticalshear point sufficient to permit pumping at high rates, and saidemulsion having an apparent rest viscosity greater than about 1000 cps.

2. The jet and rocket thixotropic emulsion fuel of claim 1, alsoincluding finely divided combustible solids.

3. The jet and rocket thixotropic emulsion fuel of claim 1, alsoincluding finely divided aluminum particles.

4. The emulsion fuel of claim 1 wherein said hydrocarbon is presenttherein in an amount of at least 90% by volume of said emulsion.

5. The jet and rocket thixotropic emulsion fuel of claim 4, alsoincluding finely divided combustible solids.

6. The jet and rocket thixotropic emulsion fuel of claim 4, alsoincluding finely divided aluminum particles.

7. The method of providing jet and rocket power comprising burning thefuel of claim 1 in a reaction motor and utilizing the products ofcombustion as a source of power.

8. The method of providing jet and rocket power comprising burning thefuel of claim 2 in a reaction motor and utilizing the products ofcombustion as a source of power.

9. The method of providing jet and rocket power comprising burning thefuel of claim 3 in a reaction motor and utilizing the products ofcombustion as a source of power.

10. The method of providing jet and rocket power comprising burning thefuel of claim 4 in a reaction motor and utilizing the products ofcombustion as a source of power.

11. The method of providing jet and rocket power comprising burning thefuel of claim 5 in a reaction motor and utilizing the products ofcombustion as a source of power.

12. The method of providing jet and rocket power comprising burning thefuel of claim 6 in a reaction motor and utilizing the products ofcombustion as a source of power.

References Cited UNITED STATES PATENTS 3,164,503 l/1965 Gehrig 149183,242,019 3/1966 Gehrig 149 -74X BENJAMIN R. PADGETT, Primary Examiner.

1. A JET AND ROCKET THIXOTROPIC HYDROCARBON-IN-WATER EMULSION FUELCOMPRISING (1) WATER, (2) AN EMULSIFIABLE HYDROCARBON, AND (3) ANEMULSIFYING AGENT, SAID HYDROCARBON BEING PRESENT IN SAID EMULSION FUELIN AN AMOUNT OF AT LEAST 80% HYDROCABON BY VOLUME OF THE EMULSION, SAIDEMULSION HAVING THE CHARACTERISTICS OF A SOLID FUEL WHEN AT REST AND THECHARACTERISTICS OF A LIQUID FUEL WHEN A FORCE IS EXERTED ON IT, SAIDEMULSION TENDING TO BE NONADHESIVE, SAID EMULSION HAVING A CRITICALSHEAR POINT SUFFICIENT TO PERMIT PUMPING AT HIGH RATES, AND SAIDEMULSION HAVING AN APPARENT REST VISCOSITY GREATER THAN ABOUT 1000 CPS.7. THE METHOD OF PROVIDING JET AND ROCKET POWER COMPRISING BURNING THEFUEL OF CLAIM 1 IN A REACTION MOTOR AND ULTILIZING THE PRODUCTS OFCOMBUSTION AS A SOURCE OF POWER.